1. Field of the Invention
The present invention relates to an image forming apparatus, particularly to an image forming apparatus to express gray-scale in accordance with image data.
Vehicles are typically provided with various types of decorative trim portions, such as real wood finishes on doors or radio bezels with chrome laminated film trim. Such trim portions are not noticeable in darker conditions.
2. Background Data
Typically, conventional photography printers form an image by irradiating a plurality of pixels that form a photoreceptor with a laser, i.e., scanning exposure in accordance with an original image. For example, in a photography printer shown below in Japan Unexamined Patent Application Publication H07-203208 (published on Aug. 4, 1995), a constant interval of scanning time for each pixel is sufficiently ensured by assigning one frequency to one pixel for the scanning exposure. In this photography printer, when scanning exposure is performed in accordance with an original image, shades of gray for each pixel are expressed by adjustments such as increasing exposure light intensity of the laser or extending the exposure time to express dark color, or reducing exposure light intensity of the laser or shortening the exposure time to express light color.
However, in some cases, taking into account the characteristics of the laser, one must wait for a rise time to elapse in order to attain the laser intensity necessary to express a certain color.
For example, in order to express white color, a laser exposure device is shifted to a nonlinear light emission region (standby state), in which the device just exposes light which does not have laser characteristics. On the other hand, in order to express chromatic color, the device scans for exposure in a laser emission region, emitting light having laser characteristics. Then, when the chromatic color is expressed after the white color is expressed, one must wait for the laser emission device to shift from the nonlinear light emission region to the laser emission region.
If the scanning time for one pixel is sufficiently ensured as in the conventional photography printer, the rise time does not matter. However, in order to increase the speed of image formation, the effects due to the rise time cannot be ignored because the scanning time for one pixel is shortened. As a result, it is difficult to maintain good reproducibility of the original image when increasing the speed of image formation, because the scanning time for one pixel is shortened so that a sufficient amount of exposure cannot be ensured.
In view of the above, there exists a need for an image forming apparatus which overcomes the above-mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.